I run a Mark IV combo which is pretty complicated, I think the Mark iii head is a little more user friendly. I guess all I can suggest is that you realize the Mark series amps require some time to get the settings where you want them. I think the Mark iii isn't as complex as the IV, but you should give yourself some time to work it. In the end, the tones are out of this world and cut through a mix like nothing else, but they do take some time to get used to.
The Boogie board is a good place to go for advice on settings, tubes, etc.
All I can say is enjoy the amp, they are remarkable. I would take a bullet for my Boogie.